Unmanned aerial vehicle (uav) beam forming and pointing toward ground coverage area cells for broadband access

ABSTRACT

Systems and methods configured to form and point beams from an unmanned aerial vehicle (UAV) toward target cells in a coverage area on the ground. One embodiment determines and forms the required number of UAV fixed beams needed to cover the target area when UAV is at its highest altitude and highest roll/pitch/yaw angles so that the target coverage area is covered under all UAV altitude and orientation conditions. In another embodiment, UAV determines the beam pointing angles toward different cells on the ground using information on position coordinates and orientation angles of the UAV, and the position coordinates of the cells in the coverage area relative to the center of coverage area. In another embodiment, a reference terminal placed at the center of coverage is used by the UAV to optimally point a beam toward center of the coverage area.

RELATED APPLICATIONS

This application is related to co-owned, co-pending, U.S. patentapplication Ser. No. 14/486,916, entitled “ANTENNA BEAM MANAGEMENT ANDGATEWAY DESIGN FOR BROADBAND ACCESS USING UNMANNED AERIAL VEHICLE (UAV)PLATFORMS”, filed on Sep. 15, 2014, co-owned, co-pending, U.S. patentapplication Ser. No. 14/295,160, entitled “METHODS AND APPARATUS FORMITIGATING FADING IN A BROADBAND ACCESS SYSTEM USING DRONE/UAVPLATFORMS”, filed on Jun. 3, 2014, co-owned, co-pending, U.S. patentapplication Ser. No. 14/222,497, entitled “BROADBAND ACCESS TO MOBILEPLATFORMS USING DRONE/UAV”, filed on Mar. 21, 2014, and co-owned,co-pending. U.S. patent application Ser. No. 14/223,705, entitled“BROADBAND ACCESS SYSTEM VIA DRONE/UAV”, filed on Mar. 24, 2014, each ofthe foregoing incorporated by reference herein in its entirety.

COPYRIGHT

A portion of the disclosure of this patent document contains materialthat is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patent documentor the patent disclosure, as it appears in the Patent and TrademarkOffice patent files or records, but otherwise reserves all copyrightrights whatsoever.

BACKGROUND

1. Technological Field

The present disclosure describes aspects of a system for broadbandinternet access using unmanned aerial vehicles (UAVs) to relay internettraffic among different types of terminals. The present disclosuredescribes systems and methods for optimally pointing the beams of a UAVtoward a coverage area on the ground, and adjusting the beams toward theground coverage area based on the UAV's altitude, movements, and motions(such as roll/pitch).

2. Description of Related Technology

As internet traffic has increased, new technologies are needed todeliver broadband access to homes and enterprises at lower cost and toplaces that are not yet covered. Examples of current broadband deliverysystems include terrestrial wired networks such as DSL (DigitalSubscriber Line) on twisted pair, fiber delivery systems such as FiOS(Fiber Optic Service), and geo-stationary satellite systems. The currentbroadband access systems have a number of short comings. One issue isthat there is a lack of service provided to remote and/or lightlypopulated areas. Geo-stationary satellites do provide service in remoteareas of the developed world such as the United States. However, poorerareas of the world lack adequate satellite capacity.

A notable reason satellite capacity has not been adequately provided inpoorer regions of the world is the relatively high cost of satellitesystems. Due to adverse atmospheric effects in satellite orbits,satellite hardware must be space qualified and is costly. Launchvehicles to put the satellites in orbit are also costly. Moreover, dueto the launch risk and the high cost of satellites, there may besignificant insurance costs for the satellite and the launch. Therefore,broadband satellite systems and services are relatively costly anddifficult to justify, particularly in poorer regions of the world. It isalso costly to deploy terrestrial systems such as fiber or microwavelinks in lightly populated regions. The small density of subscribersdoes not justify the deployment cost.

Hence what are needed are improved methods and apparatus for providingbroadband access to consumers. Ideally such methods and apparatus wouldrely on an inexpensive technology which avoids costs associated withlaunching and maintaining satellites.

SUMMARY

The present disclosure describes, inter alia, systems and methods foroptimally pointing the beams of an unmanned aerial vehicle (UAV) towarda coverage area on the ground, and adjusting the beams toward the groundcoverage area based on the UAV's altitude, movements, and motions (suchas roll/pitch).

In a first aspect, an unmanned aerial vehicle (UAV) apparatus configuredto form antenna beams toward at least one target coverage cell isdisclosed. In one embodiment the UAV apparatus includes: an antennafixture configured to form at least one beam: a set of radiotransmitters and receivers configured to transmit and receive signals toa set of ground terminals within the at least one target coverage cell:a processor sub-system; and a non-transitory computer readable medium.In one exemplary embodiment, the non-transitory computer readable mediumincludes one or more instructions which, when executed by the processorsub-system, is configured to cause the UAV apparatus to: generate atleast one beam that covers the at least one target coverage cell wherethe generated at least one beam encompasses at least one ground terminalof the set of ground terminals.

In one variant, the one or more instructions are further configured tocause the UAV apparatus to: compute a required number of fixed beams tocover the at least one target coverage cell under a plurality of UAValtitudes and orientation angles; and the generated at least one beamcomprises the computed number of fixed beams.

In another variant, the non-transitory computer readable medium isfurther configured to store one or more first position locationcoordinates corresponding to one or more coverage areas:

where for at least one coverage area of the one or more coverage areas,the non-transitory computer readable medium is further configured tostore one or more second position location coordinates of target cellsrelative to a center of the at least one coverage area; and where thenon-transitory computer readable medium further comprises one or moreinstructions that are configured to cause the UAV apparatus to: obtainone or more third position location coordinates and orientation anglesof the UAV apparatus based on at least one of a gyroscope, anaccelerometer and a position location sub-system; and compute one ormore pointing angles from the antenna fixture toward the target cellsbased at least in part on the second position location coordinates, thethird position location coordinates, and the orientation angles of theUAV apparatus.

In still another variant, the antenna fixture is configured to receive areference signal from a reference terminal associated with the at leastone target coverage cell; measure one or more signal qualitymeasurements based on the reference signal received from the referenceterminal; and determine one or more pointing angles toward the referenceterminal that optimizes the measured one or more signal qualitymeasurements.

In another variant, the one or more instructions are further configuredto cause the UAV apparatus to determine one or more relative positioncoordinates of one or more cells in one or more rings of cellssurrounding a central cell associated with the at least one targetcoverage cell. In one such case, the one or more instructions arefurther configured to cause the UAV apparatus to determine a Round TripDelay (RTD) between the UAV apparatus and the reference terminal;estimate the altitude of the UAV based at least in part on the RTD; andcompute one or more pointing angles for each beam from the UAV apparatusbased at least in part on one or more orientation angles, the estimatedaltitude, and the one or more relative position coordinates of the oneor more cells in the one or more rings of cells surrounding the centralcell.

In still another such implementation, the antenna fixture is comprisedof multiple antenna sub-apertures, where each sub-aperture is configuredto form at least one beam; each sub-aperture is controlled by anactuator; and the one or more instructions are further configured tocause the actuators to: point each sub-aperture toward a correspondingcell according to the computed pointing angles.

In other such variants, the antenna fixture is comprised of multipleantenna elements spaced apart at substantially half wavelengthdistances; the antenna sub-system comprises circuitry configured tophase the multiple antenna elements to form and point beams; and the oneor more instructions are further configured to cause the antennasub-system to point the beams according to the computed pointing angles.For example, in one such variant, the antenna fixture comprises multipleantenna elements spaced apart at substantially half wavelengthdistances: the antenna sub-system is configured to phase the multipleantenna elements to form and point beams.

In one aspect of the present disclosure, a reference terminal apparatusconfigured to generate a reference signal is disclosed. In oneembodiment the reference terminal apparatus includes: an antenna fixtureconfigured to transmit a reference signal; a processor sub-system; and

a non-transitory computer readable medium comprising one or moreinstructions. In one exemplary embodiment, the one or more instructions,when executed by the processor sub-system, are configured to cause thereference terminal apparatus to: transmit the reference signal; searchfor a reference signal response sent by an unmanned aerial vehicle(UAV); measure the signal quality of the reference signal response; anddetermine a Round Trip Delay (RTD) between the UAV and the referenceterminal apparatus based on the reference signal response.

In one variant, the antenna fixture is configured to generate a beamwhich is narrower than an orbit of the UAV. In such variants the antennafixture may additionally be configured to iteratively generate the beamwithin at least one sub-region of the orbit of UAV. In one suchexemplary case, the iteratively generated beam within the at least onesub-region is generated for a duration of time which is substantiallyequal to a cruising orbit duration of the UAV.

In another variant, the antenna fixture is configured to generate a beamwhich completely encompasses an orbit of the UAV.

Other variants may be further configured to transmit one or morelocation coordinates corresponding to one or more target cell coverageareas.

In a third aspect, a method for forming antenna beams toward at leastone target coverage cell is disclosed. In one embodiment the methodincludes: determining a first location coordinate of an aerial platform:determining an orientation of the aerial platform; identifying one ormore second location coordinates associated with the at least one targetcoverage cell: computing one or more pointing angles based at least inpart on the first and one or more second location coordinates and theorientation; and generating at least one beam that covers the at leastone target coverage cell based on the computed one or more pointingangles.

In one such variant, the first location coordinate comprises one or moreof a latitude coordinate, a longitude coordinate, and an altitude.

In another such variant, the one or more second location coordinate isreceived via a message sent from a reference terminal associated withthe at least one target coverage cell. In other implementations, the oneor more second location coordinates are determined based on a predefinedplacement.

In still another aspect, a system for coordinating coverage provisionedfrom one or more aerial platforms for at least one target coverage cellis disclosed. In one such embodiment, the system includes: one or moreaerial platforms configured to orbit near the at least one targetcoverage cell; at least one reference cell associated with the at leastone target coverage cell; where the one or more aerial platforms areconfigured to receive a reference signal generated by the at least onereference cell and responsively determine at least one pointing anglethat optimizes a signal quality metric of the received reference signaland generate one or more beams based on the at least one pointing angle.

These and other aspects shall become apparent when considered in lightof the disclosure provided herein.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following figures, where appropriate, similar components areidentified using the same reference label. Multiple instances of thesame component in a figure are distinguished by inserting a dash afterthe reference label and adding a second reference label.

FIG. 1 is a graphical depiction of an exemplary aerial platform basedcommunications system useful in conjunction with various embodimentsdescribed herein.

FIG. 2A is a graphical depiction of exemplary radio equipment of anaerial platform useful in conjunction with various embodiments describedherein.

FIG. 2B is a graphical depiction of exemplary radio equipment of aground terminal useful in conjunction with various embodiments describedherein.

FIG. 3 is a graphical depiction of an exemplary set of beams formed bythe aerial platform/UAV on the ground.

FIG. 4 is a graphical depiction of an exemplary cruising area of theaerial platform/UAV and the related coverage areas on the ground.

FIG. 5 is a graphical depiction of an exemplary aerial platform/unmannedaerial vehicle (UAV) at a given altitude and a network of beams formedover the coverage area on the ground.

FIG. 6A is graphical depiction of an exemplary unmanned aerial vehicle(UAV) antenna structure that is configured to form beams toward thecoverage area via mechanical actuators.

FIG. 6B is graphical depiction of an exemplary unmanned aerial vehicle(UAV) phased array antenna structure that is configured to form beamstoward the coverage area via electronic beam forming.

FIG. 6C is graphical depiction of a phased array beam forming approachuseful in conjunction with the phased array antenna structure of FIG.6B.

FIG. 7 is a logical flow chart of one exemplary process for determiningthe beam pointing angles from the unmanned aerial vehicle (UAV) towardthe different cells on the ground.

FIG. 8 is a logical flow chart of one exemplary process for determiningthe altitude of the unmanned aerial vehicle (UAV) according to an aspectof the disclosure.

FIG. 9 is a flow chart of one exemplary process for determining the beampointing angles from the UAV toward the different cells on the ground.

All Figures © Copyright 2014 Ubiqomm, LLC. All rights reserved.

DETAILED DESCRIPTION

This disclosure describes aspects of a system designed to providebroadband access. As used herein, the terms “unmanned aerial vehicle”(UAV), “aerial platform”, “drone”, refer generally and withoutlimitation to: drones, unmanned aerial vehicle (UAV), balloons, blimps,airships, etc. The aerial platforms may comprise propulsion systems,fuel systems, and onboard navigational and control systems. In oneexemplary embodiment, the aerial platform comprises a fixed wingfuselage in combination with a propeller, etc. In other embodiments, theaerial platform comprises a robocopter, propelled by a rotor. The aerialplatform may carry fuel onboard or function using solar energy.

FIG. 1 shows one exemplary embodiment of an unmanned aerial vehicle(UAV) 110. As shown, the exemplary UAV 110 has a drone radio sub-system112, a message switch sub-system 116, and at least one drone antennaaperture sub-system 114. UAVs communicate with at least two kinds ofground terminals: one type are user Ground Terminal (GT) 120, such asterminals at home or enterprises to provide internet connectivity tohome or enterprise (such as e.g., the Internet); a second type isreferred to as the internet Gateway (GTW) 130 which is connected to theInternet. Note that embodiments described below apply to fixedterminals/devices on the ground, as well as mobile terminals/devicesattached to platforms such as vehicles, boats, ship, airplanes, trucks,etc., and standalone mobile devices (e.g., handheld devices, etc.). Theterm “device”, as used hereinafter may broadly encompass any of theaforementioned platforms (e.g., the drone 110, the GT 120, and/or theGTW 130). During operation, the UAV is configured to cruise or patrol an“orbit”, and provide connectivity between the ground terminal (GT) 120and other GT 120 and/or gateway terminals (GTW) 130. The GTWs 130 may beconnected to broader internet networks 136, thereby allowing the GT 120internet access and/or access to other GT or GTW.

FIG. 2A illustrates one exemplary embodiment of an unmanned aerialvehicle (UAV) radio sub-system 112 that includes five (5) sub-systems: areceiver 318 that is configured to demodulate and decode a signalreceived from a drone antenna aperture sub-system 114: a transmitter 316that is configured to modulate data received from a processor 314 andsend the resulting signal through the drone antenna aperture sub-system114; a processor sub-system 314 that is configured to carry outfunctions such as: (i) configuring the receiver 318 and transmitter 316sub-systems, (ii) processing the data received from the receiver 318sub-system, (iii) determining the data to be transmitted through thetransmitter sub-system 316, and (iv) controlling the antenna sub-system114; a non-transitory computer readable memory sub-system 312 that isconfigured to store one or more program code instructions, data, and/orconfigurations, and system parameter information that are accessed bythe processor 314; and a gyroscope/accelerometer/Global PositioningSystem (GPS) sub-system 319 that is configured to determine a positionand orientation of the UAV such as roll/pitch angles.

Depending on the altitude of the UAV, each UAV covers an area on theground with a radius of as low as a few 10s of kilometers (km) and asmuch as 200 km or more. GTs 120 transmit and receive data from theinternet using the UAV 110 as intermediary to the GTW 130. The UAV'sradio sub-system aggregates traffic received from the GTs within thecoverage area of the UAV of a population of GTs (in some implementationsthe UAV may aggregate traffic from as many as all GTs and as few as oneGT) and sends the aggregated data to the internet via one or more of theGTWs. Since, the GTWs handle aggregated data from multiple GTs,practical implementations of the present disclosure may support higherdata rates between the UAV and the GTW, than between the UAV and the GT.Accordingly, in one embodiment the gain of the GTW antenna sub-system ismuch larger than that of the GT, and the GTW transmitter transmits athigher power than the GTs. Those of ordinary skill in the related artswill readily appreciate the wide variety of techniques which may be usedto increase gain, including without limitation, increasingtransmit/receive power, increasing bandwidth, increasing processinggain, increasing coding gain, etc.

Referring back to FIG. 1, the GT 120 has two main sub-systems, a groundterminal radio sub-system 122, and a ground terminal antenna sub-system124. As shown in FIG. 2B, the GT radio sub-system 122 comprises 4sub-systems: the receiver 418 that demodulates and decodes the signalfrom the drone antenna sub-system; the transmitter sub-system 416 thatmodulates the data and sends the resulting signal through the antennasub-system 124; the processor sub-system 414 that carries out functionssuch as: configuring the receiver 418 and transmitter 416 sub-systems,processing the data received from the receiver 418 sub-system,determining the data to be transmitted through the transmittersub-system 416, as well as controlling the antenna sub-system 124; andthe memory sub-system 412 that contains program code, configurationdata, and system parameters information that are accessed by theprocessor 414.

The desired target coverage area on the ground is divided into a numberof cells; one such exemplary division is shown as an arrangement ofthirty seven (37) hexagonal cells in FIG. 3. The aerial platform formsbeams to cover each cell on the ground in its target coverage area. Asshown, the UAV generates thirty seven (37) beams corresponding to thehexagonal cells: e.g., one (1) “central beam” and three (3) rings ofbeams around the central beam, on the ground. Hexagons show the idealcoverage of each beam. In reality the beams overlap as shown by thedashed circles. In this exemplary example, the available frequencybandwidth is divided into three (3) bands (F1, F2 and F3), and the three(3) frequency bands are assigned to adjacent beams in such a way that notwo neighboring beams use the same frequency. The foregoing frequencyallocation scheme is described as having a “frequency reuse” of three(3). The three (3) different dotted circle types indicate beams that usedifferent frequency bands. Those of ordinary skill in the related arts,given the contents of the present disclosure, will readily appreciatethat other frequency reuse schemes and/or cell divisions may beinterchangeably used with equal success.

Aerial platforms such as UAVs cruise/patrol in a three dimensional space(e.g., latitude, longitude, and altitude). The position of the aerialplatform/UAV with respect to the terminals on the ground changes as theaerial platform/UAV moves horizontally and vertically within itscruising orbit (e.g., a circle, figure eight, clover leaf, etc.).

Those of ordinary skill will readily appreciate that the beams generatedby the UAV radiate out as a function of distance from the UAV, thus ifadjustments are not made to the beams generated by the UAV based onmovements of the UAV, then the beam footprint will be larger (orsmaller) than is desired. For example, if the UAV moves vertically, thecoverage area on the ground that is illuminated by the aerialplatform/UAV's antenna sub-system 114 will change. FIG. 4 illustratesthe cruising area of the aerial platform. The top solid circle 610 showsthe cruising orbit of the aerial platform/UAV when the platform is atits highest possible altitude. The lower dotted circle 612 shows thecruising orbit when the platform is at its lowest cruising altitude. Forclarity, the overarching hexagonal cells are not shown in the coveragearea to simplify FIG. 4 and allow overlay of multiple coverage areascorresponding to different scenarios for comparison thereof as describedsubsequently herein. During normal operation, the aerial platformcruises within an orbit at a particular altitude: however over thecourse of the day the aerial platform will move vertically up or downdepending on time of day. For instance, solar powered drones may need torun on batter power at night; since the drone must conserve its energyit may reduce its altitude.

Consider one exemplary UAV antenna sub-system that is designed so as tocreate a fixed set of beams on the ground to cover a certain area shownby the solid circular shape 614 at the bottom of FIG. 4 when the UAV isat the highest altitude. Then, when the UAV moves down to the lowestaltitude, the coverage area provided by the set of fixed beam willshrink to a smaller area as shown by dashed circular shape 616 at thebottom of FIG. 4. For instance, in one practical implementation, thehighest altitude of the UAV is 25 km and the radius of the coverage ofthe UAV on the ground is planned for 25 km. If the aerial platform'santenna beams are static/fixed, then as the UAV moves down to thealtitude of 20 km the coverage area of the UAV will also shrink to 20 kmon the ground. In order to compensate for this reduction in coverage,the aerial platform antenna system should be designed, as describedlater in this disclosure, to ensure that the desired target coveragearea is always illuminated as the UAV altitude changes. While theforegoing example is presented within the context of altitude changes,those of ordinary skill in the related arts given the contents of thepresent disclosure will readily appreciate, that the aerial platform/UAVmay also change its orientation, such as its roll/pitch/yaw, as itcruises in its orbit. If the beams formed by the aerial platform'santenna sub-system are static/fixed, then as the aerial platform rollsup toward one side, the coverage area illuminated by the UAV's antennasub-system 110 will correspondingly shift and some areas in the targetcoverage area may lose coverage. The dotted shape 618 at the bottom ofFIG. 4 shows how the coverage area has shifted to the right when theaerial platform rolls up toward the right side.

Therefore, in order to provide coverage in a desired target area on theground at all time, the aerial platform beam generation and beampointing mechanism must take into account at least three types of aerialplatform/UAV movements (or six degrees of freedom): (i) horizontalmotion (e.g., a circular cruising orbit), (ii) vertical motion, and(iii) orientation (roll, pitch, yaw).

Static Fixed Beam Example #1

To these ends, in one exemplary aspect of the present disclosure anaerial platform is configured statically with fixed beams so as toaccommodate coverage deviations due to e.g., changes in (i) horizontalmotion (e.g., a circular cruising orbit), (ii) vertical motion, and(iii) orientation (roll, pitch, yaw). In one such embodiment, the aerialplatform's antenna sub-system forms static/fixed beams are not changeddynamically based on orientation or altitude of the platform; instead,the aerial platform ensures coverage regardless of the altitude andorientation by creating more beams when the platform is at the lowestaltitude (or worst case altitude). In other words, the fixed/staticbeams are designed to ensure coverage at the lowest altitude (ororientation).

In another embodiment, the aerial platform creates enough beams to coverthe target coverage area on the ground for the condition where theaerial platform is at the altitude half way between the highest and thelowest altitudes. Note that typically the beam's gain at the cell edgeis 2 to 3 dB lower than that of peak gain at the center of the cell, andthe beam's gain rolls off beyond the cell edge. Therefore, the aerialplatform beam will provide coverage to terminals that are placed beyondthe cell edge, but at lower gains than at the cell edge. In this case,as the aerial platform moves to the lowest altitude the coverage area ofthe beams shrink but since, as mentioned above, the beams do providecoverage in a larger area than the specific cell, then the targetcoverage area will receive service but at lower beam gain. As the aerialplatform moves to the highest altitude, the beams expand and cover alarger area than the target coverage area. In cases where the differencebetween the highest and lowest altitudes are relatively small, then oneneed not turn off any beams when aerial platform is at the highestaltitude as the extra coverage beyond the target area will be small.

In some implementations, the static fixed beam approach may create otherproblems: for example, when the UAV moves to the highest altitude thenits beam will expand outside the target coverage area, which will resultin inefficient use of the UAV communications resources. Additionally,more beams must be added to take into account the maximum roll theplatform may undergo at the lower altitude. These extra beams are notused when the platform is at the highest altitude and low roll angles,further reducing efficiency. For illustration, consider the example ofthe highest and lowest possible platform altitudes of 25 and 20 km. anda target coverage area on the ground of radius 25 km. According to theaforementioned static/fixed aerial platform beam design, the drone mustbe designed with enough beams to cover an area of radius ˜31.25 km onthe ground when the platform is at 25 km altitude so that when theplatform descends to a 20 km altitude a coverage area of at least 25 kmwill be maintained on the ground. In this example the drone must provideabout 56% more coverage than is needed at the highest altitude, in orderto ensure adequate coverage at the lowest altitude. Note that if thedifference between the highest and lowest platform altitude is more than5 km, then as this inefficiency becomes even more exaggerated.Additional beams will also be needed to account for the platforms roll.Under such a design methodology, the drone may need to support twice thenumber of beams for undesirable conditions (e.g., at lowest altitude andhigh UAV roll angles) as would be needed for the optimal conditions(e.g., at highest altitude and low UAV roll angles).

Accordingly, the following variants provide improved schemes for aerialplatform beam forming techniques to dynamically adjust the beams of theaerial platform/UAV depending on the horizontal displacement, altitude,and orientation of the platform, in order to minimize the number ofbeams needed. Consider first the effect of the movement of the aerialplatform around the circle. The projected network of beams, such as theone illustrated in FIG. 5, will follow the aerial platform's movementaround its circular cruising orbit 610. For example, the center of thecoverage area 519 on the ground is the projection of the center of thecircular orbit of the aerial platform/UAV 518. The antenna fixture 114that is installed under the aerial platform/UAV is fixed and will notdirectly point toward the center of coverage 519 on the ground.Accordingly, the aerial platform antenna beam forming and beam pointingmechanism should be designed to ensure that the beams formed by theaerial platform cover the coverage area 614 on the ground given therelative location of the aerial platform/UAV, and its antenna fixture,with respect to the center 519 of desired coverage area on the ground.

In one such variant, the extra beams are unnecessary when the platformis at the highest altitude and/or low roll angles. To these ends theaerial platform may simply enable/disable the extra beams based onaltitude and/or orientation angle. For example, above a first altitudethreshold, the extra beams are disabled, below a second altitude theextra beams are enabled. The first and second thresholds may be furtherselected to provide some hysteresis (e.g., to prevent beam“flickering”). Similarly, extra beams may be enabled/disabled based onorientation angles.

In another exemplary variant, the aerial platform may form/point beamsto compensate for altitude/orientation. For example, in one suchembodiment, the aerial platform forms a beam to cover the central cell 1shown with dashed line in FIG. 5. One such implementation may point abeam toward the center of the coverage area based on knowledge of theposition location coordinates and the roll of the aerial platform. Forexample, the aerial platform may use an onboardgyroscope/accelerometer/Global Positioning System (GPS) sub-system 319to determine the orientation and position coordinates of the aerialplatform. The aerial platform processor sub-system 314 uses thedetermined position location and orientation of the aerial platform aswell as the position coordinates of the center of the coverage area tocalculate the angle 810 from a line from the aerial platform to thecenter of the coverage area relative to a line perpendicular from aerialplatform to ground, and instructs the radio sub-system 112 and theantenna sub-system 114 to point its beam toward the central cell 1 atthe computed angle.

While the scenario shown in FIG. 5 does not show any aerial platformroll, pitch, or yaw, those of ordinary skill, given the contents of thepresent disclosure, will readily appreciate that the angle of the beamfrom the aerial platform must also take into account the orientationangle of the platform in addition to the angle 810. The orientationangle must be subtracted or added to angle 810 depending on the platformorientation.

Next, the aerial platform can calculate appropriate beam projections forthe remaining cells of the desired target coverage area on the ground.First, the center of the cells of the remaining rings of cells, shown inFIG. 5, can be calculated relative to the center of the central cellbased on the desired target coverage area. Once the centers of cells forthe rings of cells are computed, then a beam from the aerial platformcan be pointed toward the center of each cell by computing the requiredpointing angle from the antenna at the aerial platform to the center ofeach cell. Once the network of beams have been pointed, then as theaerial platform moves around the circle, the network of beams on theground also move around the center of the central beam. In other words,as the aerial platform/UAV moves around a circular orbit, the network ofbeams will continue to cover the desired coverage area.

Reference Cell Example #2

In a second aspect of the present disclosure, the aerial platform isassisted by a reference terminal 120 in a location close to the desiredcenter of coverage area, e.g., substantially at the center of cell 1 inFIG. 5. In some variants, the reference terminal is incorporated withina GT 120 or GTW 130, in other variants the reference terminal is astandalone terminal. While the following examples are provided withrespect to a centrally located reference terminal, it is appreciatedthat a reference terminal which is not centrally located may be equallysuitable, so long as the drone is appraised of the reference terminal'sdisplacement from the center of coverage. In some cases, thedisplacement may be provided by the reference terminal itself: in othercases, the central cell displacement may be dynamically determined bythe drone (or e.g., network operator).

In one such embodiment, the reference terminal has an antenna thatradiates a reference signal throughout the three dimensional spacewithin which the aerial platform/UAV cruises. The aerial platformantenna sub-system 114 forms a beam toward the general area of thecenter of the coverage in order to search for the reference terminal.Specifically, the reference terminal 120 transmits a reference signal222 that is received by the aerial platform 110 radio sub-system 112.The aerial platform radio sub-system 112 measures a signal qualitymetric of the received reference signal 222, such as Signal toInterference plus Noise Ratio (SINR). Other examples of signal qualitymetrics include without limitation: received signal strength indication(RSSI), bit error rate (BER), block error rate (BLER), etc.

Next the aerial platform 110 antenna sub-system 114 perturbs or adjuststhe position of the central beam toward the reference terminal and makesa measurement of the signal quality of the received reference signal222. If the measured signal quality (such as SINR) is higher at theperturbed beam position, then the aerial platform antenna sub-system 114uses the new beam position as the nominal beam position for the centralbeam. The aerial platform 110 radio sub-system 112 continues to measuresignal quality from reference signal 222, and instructs the antennasub-system 114 to perturb the position through a search pattern (e.g., agrid search, etc.) to find the “optimal” position of the central beam.The optimal central beam position should maximize the received signalquality from the reference terminal 120. In some embodiments, the signalquality measurements made by the radio sub-system 112 at the differentcentral beam positions may be sent to the processor sub-system 314 foranalysis. The processor sub-system 314 may then run a number ofalgorithms on the measured signal quality values in order to find theoptimal beam pointing angle for the central cell.

Once the central beam is pointed toward the center of the coverage area(cell 1 in FIG. 5) as described above, the aerial platform 110 radiosub-system 112 and processor sub-system 314 determine the pointingangles for the beams toward cells in the other rings surrounding thecentral cell. In one embodiment of the disclosure, the processorsub-system 314 has knowledge of the position location coordinates andorientation angles of the aerial platform, and the location coordinatesof the desired centers of the other cells. Then, the processorsub-system 314 may compute the required pointing angle from the antennasub-system 114 for beams toward the different cells and instruct theantenna sub-system 114 to point the beams at the computed pointingangles toward each cell.

Relative Positioning Example #3

In yet another aspect of the disclosure, the aerial platform radiosub-system 112 and processor 314 may determine the beam pointing anglesfor each beam in the network relative to the central beam without directknowledge of the position coordinates of the aerial platform. The aerialplatform radio sub-system 112 makes a Round Trip Delay (RTD) measurementwith the reference terminal radio sub-system 124. To measure the RTD,the aerial platform radio sub-system 112 measures the time of arrival ofthe reference signal 222 transmitted by the reference terminal 120, andin turn transmits a message 212 to the reference terminal 120. Thereference terminal 120 measures the time of arrival of the message 212,and computes the RTD based on the time of transmission of referencesignal 222 and time of arrival of message 212. Those of ordinary skillin the related arts will readily appreciate that the RTD measurement maybe performed in a variety of other manners, the foregoing being purelyillustrative.

Since there may be processing and transmission queuing delays at theaerial platform radio sub-system 112 before the message 212 istransmitted to the reference terminal 120 in response to reception ofreference signal 222; in order to improve accuracy, the radio sub-system112 may include the processing and transmission delays (or a bestestimate thereof) in the message 212 sent to the reference terminal.Thereafter, reference terminal 120 can appropriately correct the delaysdue to processing/queuing delays in computing the RTD values.

The processor 314 uses the RTD measurement to estimate the distance fromthe aerial platform 110 to the reference terminal 120 (e.g., based onthe rate of propagation of radio waves). FIG. 5 illustrates the cruisingorbit of the aerial platform/UAV and the beam network on the groundrelative to the UAV. Since the aerial platform/UAV cruises in a smallcircle 610 around a point 518 above the center of coverage, and thealtitude of the aerial platform/UAV is much larger than the radius 516of the cruising orbit, then the distance from the UAV to the center ofcoverage 512 as measured by the RTD is very close to the actual altitudeof the aerial platform 514. Therefore, the distance measured by the RTDas described above can be used as a close approximation to the altitudeof the UAV 110. The processor 314 has knowledge of the desired centersof the different beams on the ground for a given altitude of the UAV.For instance, once the aerial platform 110 has formed a beam on thereference terminal, then the reference terminal 120 may send informationon the number of cells and the center of cells for different altitudesto the aerial platform 110. Then, the aerial platform processor 314 usesposition coordinates of the center of each cell in the surrounding rings(or tiers) of cells relative to the center cell, the orientation angleof the UAV, and altitude of the UAV to compute the required pointingangle of the beams from the aerial platform antenna sub-system 114toward the center of each cell. Once the pointing angle from the antennasub-system 114 toward each cell center is computed by the processor 314,then the antenna sub-system points beams toward each cell at thecomputed pointing angles.

Narrow Beam Reference Cell Example #4

In another aspect of the disclosure, the reference terminal may have anarrow beam width antenna beam which may not cover the entire threedimensional space within which the aerial platform cruises. Depending onthe relative position of the aerial platform and the direction thereference terminal is pointing its beam, the aerial platform radiosub-system 112 may not be able to detect the reference signal 222 fromthe reference terminal 120.

In one exemplary embodiment, in order to ensure that the referenceterminal 120 is pointing a beam toward at least part of the cruisingorbit of the UAV, the reference terminal processor sub-system 314divides the space that contains the UAV's three dimensional cruisingarea into sub-regions. Each sub-region is small enough so that theaerial platform's beam can respond within the sub-region when the aerialplatform's beam receives the reference signal.

During a search, the reference terminal antenna sub-system 124iteratively points its beam toward different sub-regions, and in eachsub-region the reference terminal radio sub-system 122 searches for thereference signal response 212 sent by the aerial platform 110. In onesuch variant, the reference terminal maintains its beam fixed in eachsub-region for the duration of the UAV's orbit, so that the UAV willhave made at least one complete orbit during the search. This ensuresthat the UAV and the reference terminal beams will be aligned longenough to allow detection of reference signal 212 by the referenceterminal radio sub-system 122, and that the reference terminal 120 willbe able to detect the aerial platform's reference signal 212 when theaerial platform enters the sub-region. This search process continuesuntil the reference terminal's radio sub-system 122 detects thereference signal response 212 from the aerial platform 110. Once thereference terminal 120 has detected the reference signal response 212,then it sends a message 222 to the aerial platform. Thereafter, theaerial platform 110 may optimize the pointing of its central beam towardthe central cell using one of the embodiments described above. Since theaerial platform is moving in its cruising orbit, the aerial platformcentral beam pointing process and RTD measurements must be carried outduring the time period when the reference terminal's beam is pointingtoward the aerial platform.

After the initial pointing of the aerial platform's beams toward thedifferent cells on the ground using the systems and methods described inthe above embodiments, the aerial platform 110 sub-systems will continueto update the position location coordinates, orientation angle, andaltitude of the platform. Based on the updates of the UAV positionlocation and orientation angles, the aerial platform sub-systems maycompute new beam pointing angles toward each cell and adjust each beamaccordingly.

Beam Pointing Techniques—

The above embodiments described systems and methods for determining thepointing angle of each of the aerial platform's beams toward thedifferent cells in the desired target coverage area on the ground.Various schemes for pointing antenna beams are now described in greaterdetail.

FIG. 6A shows an exemplary antenna fixture for actuator based beamforming. As shown, the exemplary antenna fixture is composed of 7 faces,labeled as 116-j where j is the index of the different faces j=1 . . . ,7. Face 160-1 covers the area under the aerial platform that is closerto the center of coverage. The trapezoidal base of the antenna fixtureis attached to underneath the aerial platform. Faces 116-2 through 116-6cover areas that are father from the center of coverage of the UAV. Eachantenna face 116-j comprises multiple antenna sub-apertures 117-k, wherek is the label of different sub-apertures. Each sub-aperture 117-kgenerates one beam toward one cell of the coverage area. Each antennasub-aperture 116-j is attached to an actuator 119-k which is controlledby processor 314. Once the processor 314 has computed the pointingangles of each antenna sub-aperture 116-k, it instructs the actuator119-k to tilt the sub-aperture 117-k according to the computed pointingangle.

In one aspect of the antenna system design, the antenna beam iselectronically formed via e.g., a phased array, to point the beams thatcover each cell on the ground. As shown in FIG. 6B, each antenna facecontains multiple antenna elements 115-j spaced at substantially halfthe transmission and/or reception wavelength, where j is the label ofthe different antenna elements. In most practical applications, thetransmission and reception wavelengths are not significantly different(e.g., only differing by a few megahertz, at gigahertz frequency carrierranges), accordingly the half wavelength distance is predominantly basedon the carrier frequency. However, those of ordinary skill in therelated arts will readily appreciate, given the contents of the presentdisclosure, that where the transmission and reception wavelengths aresubstantially separated, the half wavelength distance would be differentbetween transmission and reception antenna fixtures.

Once the processor 314 has computed the pointing angles for beams towardeach cell on the ground, it instructs the antenna sub-system 114 to formbeams toward each cell at the corresponding pointing angles. FIG. 6Cillustrates a phased array beam forming approach where the antennasub-system 114 forms each beam by multiplying the signal destined forthe k-th beam by coefficients C_(jk) (j=1 . . . , N) and sending theresults to a subset of N antenna elements 115-1 through 115-N.

Artisans of ordinary skill in the related arts, given the contents ofthe present disclosure, will readily appreciate that other mechanicaland/or electronic beam forming/pointing antenna structures may beinterchangeably and/or additionally used in conjunction with themechanical and/or electronic beam forming/pointing antenna designdescribed above. Various other antenna element structures such asmetamaterials, slot arrays, etc, may also be used with equal success.

FIG. 7 is a flow chart of one exemplary method for determining pointingangles toward each cell from the aerial platform/UAV.

In step 702, the processor 314 obtains the aerial platform'sorientation. In one exemplary embodiment, the orientation includes oneor more of a roll angle, pitch angle, and/or yaw angle.

In one exemplary embodiment, the aerial platform's orientation isdetermined on the basis of one or more of a Global Position System(GPS), accelerometers, gyroscopes, etc. Various other mechanisms usefulfor determining position are readily appreciated by those of ordinaryskill in the related arts, given the contents of the present disclosure.

In step 704, the processor 314 obtains information on the positionlocation of the aerial platform. In one exemplary embodiment theposition includes one or more of horizontal (e.g., latitude, longitude)and vertical (e.g., altitude) coordinates. In one exemplaryimplementation, the position coordinates are obtained from a GlobalPositioning System (GPS). In other implementations, the positioncoordinates may be obtained by triangulating time of arrivalmeasurements received from the radio sub-system 122 which are receivedsignals from e.g., multiple reference terminals.

In step 706, the processor sub-system 314 determines one or moreposition coordinates of target cells. In one exemplary embodiment, theone or more position coordinates may be received from a message sent byground terminal. In other embodiments, the one or more positioncoordinates may be independently derived based on e.g., a predefinedplacement. In one exemplary predefined placement, the one or moreposition coordinates correspond to thirty seven (37) cells arranged in ahexagonal pattern of three (3) concentric rings surrounding a centralcell. In still other embodiments, the processor sub-system 314 mayindependently determine when to enable/disable various target cells soas to e.g., reduce power, improve cellular coverage efficiency, reduceinterference, etc.

In step 708, processor 381 computes the pointing angle from the aerialplatform antenna system toward each cell. In one exemplary embodiment,the pointing angle is determined on the basis of trigonometricproperties, using the determined location coordinates and orientationangles. In other embodiments, the optimal pointing angle is determinedbased on a search (e.g., by testing multiple perturbations to determinean optimal pointing angle).

In step 710, the aerial platform antenna sub-system points its beams inaccordance with the computed pointing angles. In one embodiment, thepointing is mechanically actuated. In other embodiments, the pointing iselectronically performed via a phased array.

FIG. 8 is a flow chart of one exemplary method for ensuring that anantenna of a reference terminal with a narrow beam width will point to asub-region of the cruising area of the aerial platform so that at leastfor a certain period of time the aerial platform and the referenceterminal radio sub-systems can communicate and make RTD measurements.

In step 802, the reference terminal processor sub-system divides thecruising area of the platform into contiguous sub-regions and creates alist of the sub-regions. In one embodiment, the division is evenly splitbased on geography. In other embodiments, the division is unevenly splitbased on an estimated likelihood of the UAV. For example, if thereference terminal believes that a UAV is within a certain space (e.g.,based on recent history, out-of-band signaling, etc.), then thereference terminal may allocate a disproportionate amount of its searchresources (e.g., time, power, bandwidth, etc.) accordingly.

When an aerial platform successfully receives the reference signal, itresponsively transmits a response. Accordingly, at step 804, thereference terminal points its antenna beam toward a sub-region, andsearches for the response to the reference signal sent by the aerialplatform. In one exemplary embodiment, the reference terminal searcheswithin the sub-region for a duration of time which is substantiallyequal to the cruising orbit duration of the aerial platform. In otherembodiments, the duration is selected so as to maximize the probabilityof receiving a response to reference signal from the aerial platform. Inembodiments where there are multiple aerial platforms, it may not bepossible to align search periods with any single drone's orbitalduration: however, the reference terminal may intelligently select aperiod so as to maximize discovery.

In step 806, the reference terminal determines whether the referencesignal from the aerial platform has been detected. If the aerialplatform's reference signal has been detected, the process moves to step810 where the aerial platform and reference terminal perform round tripdelay (RTD) measurements to determine the altitude of the UAV.

If the reference terminal has not detected the reference signal from theaerial platform in 804, the process moves to step 808 where the recentlychecked sub-region is removed from the top of the list of sub-regions.The process then moves to step 804 where the reference terminal searchesfor the sub-region at the top of the new list.

FIG. 9 is a flow chart of one exemplary method for determining pointingangles toward each cell on the ground from the aerial platform/UAV usinga reference terminal to assist in pointing beams.

In step 902, the processor 314 obtains the aerial platform's orientationfrom the gyroscope/accelerometer sub-system 319. In one exemplaryembodiment, the aerial platform's orientation is determined on the basisof one or more of a Global Position System (GPS), accelerometers,gyroscopes, etc. Various other mechanisms useful for determiningposition are readily appreciated by those of ordinary skill in therelated arts, given the contents of the present disclosure.

In step 904, the processor 314 estimates the altitude of the aerialplatform using Round Trip Delay (RTD) measurements between the aerialplatform's radio sub-system 112 and a reference terminal's radiosub-system 124.

In step 906, the processor sub-system 314 determines one or moreposition coordinates of target cells. In one exemplary embodiment, theone or more position coordinates may be received from a message sent byground terminal. In other embodiments, the one or more positioncoordinates may be independently derived based on e.g., a predefinedplacement. In one exemplary predefined placement, the one or moreposition coordinates correspond to thirty seven (37) cells arranged in ahexagonal pattern of three (3) concentric rings surrounding a centralcell.

In still other embodiments, the processor sub-system 314 mayindependently determine when to enable/disable various target cells soas to e.g., reduce power, improve cellular coverage efficiency, reduceinterference, etc.

In step 908, processor 314 computes the pointing angle from the aerialplatform antenna system toward each cell on the ground using theestimated altitude, orientation, and position coordinates of the cells.

In step 910, the aerial platform antenna sub-system adjusts, eithermechanically or electronically, the position of each beam toward thetarget cell based on the computed pointing angle.

It will be recognized that while certain aspects of the disclosure aredescribed in terms of a specific sequence of steps of a method, thesedescriptions are only illustrative of the broader methods of thedisclosure, and may be modified as required by the particularapplication. Certain steps may be rendered unnecessary or optional undercertain circumstances. Additionally, certain steps or functionality maybe added to the disclosed embodiments, or the order of performance oftwo or more steps permuted. All such variations are considered to beencompassed within the disclosure disclosed and claimed herein.

While the above detailed description has shown, described, and pointedout novel features of the disclosure as applied to various embodiments,it will be understood that various omissions, substitutions, and changesin the form and details of the device or process illustrated may be madeby those skilled in the art without departing from the disclosure. Thisdescription is in no way meant to be limiting, but rather should betaken as illustrative of the general principles of the disclosure. Thescope of the disclosure should be determined with reference to theclaims.

It will be further appreciated that while certain steps and aspects ofthe various methods and apparatus described herein may be performed by ahuman being, the disclosed aspects and individual methods and apparatusare generally computerized/computer-implemented. Computerized apparatusand methods are necessary to fully implement these aspects for anynumber of reasons including, without limitation, commercial viability,practicality, and even feasibility (i.e., certain steps/processes simplycannot be performed by a human being in any viable fashion).

What is claimed is:
 1. An unmanned aerial vehicle (UAV) apparatusconfigured to form antenna beams toward at least one target coveragecell, comprising: an antenna fixture configured to form at least onebeam; a set of radio transmitters and receivers configured to transmitand receive signals to a set of ground terminals within the at least onetarget coverage cell; a processor sub-system; and a non-transitorycomputer readable medium comprising one or more instructions which, whenexecuted by the processor sub-system, is configured to cause the UAVapparatus to: generate at least one beam that covers the at least onetarget coverage cell; and where the generated at least one beamencompasses at least one ground terminal of the set of ground terminals.2. The UAV apparatus of claim 1, where the one or more instructions arefurther configured to cause the UAV apparatus to: compute a requirednumber of fixed beams to cover the at least one target coverage cellunder a plurality of UAV altitudes and orientation angles; and where thegenerated at least one beam comprises the computed number of fixedbeams.
 3. The UAV apparatus of claim 1, where the non-transitorycomputer readable medium is further configured to store one or morefirst position location coordinates corresponding to one or morecoverage areas: where for at least one coverage area of the one or morecoverage areas, the non-transitory computer readable medium is furtherconfigured to store one or more second position location coordinates oftarget cells relative to a center of the at least one coverage area; andwhere the non-transitory computer readable medium further comprises oneor more instructions that are configured to cause the UAV apparatus to:obtain one or more third position location coordinates and orientationangles of the UAV apparatus based on at least one of a gyroscope, anaccelerometer and a position location sub-system; and compute one ormore pointing angles from the antenna fixture toward the target cellsbased at least in part on the second position location coordinates, thethird position location coordinates, and the orientation angles of theUAV apparatus.
 4. The UAV apparatus of claim 1, where: the antennafixture is configured to receive a reference signal from a referenceterminal associated with the at least one target coverage cell; measureone or more signal quality measurements based on the reference signalreceived from the reference terminal; and determine one or more pointingangles toward the reference terminal that optimizes the measured one ormore signal quality measurements.
 5. The UAV apparatus of claim 4, wherethe one or more instructions are further configured to cause the UAVapparatus to: determine one or more relative position coordinates of oneor more cells in one or more rings of cells surrounding a central cellassociated with the at least one target coverage cell.
 6. The UAVapparatus of claim 5, where the one or more instructions are furtherconfigured to cause the UAV apparatus to: determine a Round Trip Delay(RTD) between the UAV apparatus and the reference terminal; estimate thealtitude of the UAV based at least in part on the RTD; and compute oneor more pointing angles for each beam from the UAV apparatus based atleast in part on one or more orientation angles, the estimated altitude,and the one or more relative position coordinates of the one or morecells in the one or more rings of cells surrounding the central cell. 7.The unmanned aerial vehicle (UAV) apparatus of claim 3, where: theantenna fixture is comprised of multiple antenna sub-apertures, whereeach sub-aperture is configured to form at least one beam; where eachsub-aperture is controlled by an actuator; and the one or moreinstructions are further configured to cause the actuators to: pointeach sub-aperture toward a corresponding cell according to the computedpointing angles.
 8. The unmanned aerial vehicle (UAV) apparatus of claim3, where: the antenna fixture is comprised of multiple antenna elementsspaced apart at substantially half wavelength distances; the antennasub-system comprises circuitry configured to phase the multiple antennaelements to form and point beams; and where the one or more instructionsare further configured to cause the antenna sub-system to point thebeams according to the computed pointing angles.
 9. The UAV apparatus ofclaim 7, where: the antenna fixture comprises multiple antenna elementsspaced apart at substantially half wavelength distances; the antennasub-system is configured to phase the multiple antenna elements to formand point beams.
 10. A reference terminal apparatus configured togenerate a reference signal, comprising: an antenna fixture configuredto transmit a reference signal; a processor sub-system; and anon-transitory computer readable medium comprising one or moreinstructions which, when executed by the processor sub-system, isconfigured to cause the reference terminal apparatus to: transmit thereference signal; search for a reference signal response sent by anunmanned aerial vehicle (UAV); measure the signal quality of thereference signal response; and determine a Round Trip Delay (RTD)between the UAV and the reference terminal apparatus based on thereference signal response.
 11. The reference terminal apparatus of claim10, where the antenna fixture is configured to generate a beam which isnarrower than an orbit of the UAV.
 12. The reference terminal apparatusof claim 11, where the antenna fixture is configured to iterativelygenerate the beam within at least one sub-region of the orbit of UAV.13. The reference terminal apparatus of claim 12, where the iterativelygenerated beam within the at least one sub-region is generated for aduration of time which is substantially equal to a cruising orbitduration of the UAV.
 14. The reference terminal apparatus of claim 10,where the antenna fixture is configured to generate a beam whichcompletely encompasses an orbit of the UAV.
 15. The reference terminalapparatus of claim 10, which is further configured to transmit one ormore location coordinates corresponding to one or more target cellcoverage areas.
 16. A method for forming antenna beams toward at leastone target coverage cell, comprising: determining a first locationcoordinate of an aerial platform; determining an orientation of theaerial platform; identifying one or more second location coordinatesassociated with the at least one target coverage cell; computing one ormore pointing angles based at least in part on the first and one or moresecond location coordinates and the orientation; and generating at leastone beam that covers the at least one target coverage cell based on thecomputed one or more pointing angles.
 17. The method of claim 16, wherethe first location coordinate comprises one or more of a latitudecoordinate, a longitude coordinate, and an altitude.
 18. The method ofclaim 17, where the one or more second location coordinate is receivedvia a message sent from a reference terminal associated with the atleast one target coverage cell.
 19. The method of claim 18, where theone or more second location coordinates are determined based on apredefined placement.
 20. A system for coordinating coverage provisionedfrom one or more aerial platforms for at least one target coverage cell,comprising: one or more aerial platforms configured to orbit near the atleast one target coverage cell; at least one reference cell associatedwith the at least one target coverage cell; and where the one or moreaerial platforms are configured to receive a reference signal generatedby the at least one reference cell and responsively determine at leastone pointing angle that optimizes a signal quality metric of thereceived reference signal and generate one or more beams based on the atleast one pointing angle.